Patients who are urban, poor, and suffer from chronic diseases face multiple obstacles to effective health care, beginning with limited access to health services. Homelessness, low literacy, social isolation, language barriers, addiction, and mental illness can all thwart effective teatment. Ineffective healthcare results in excess morbidity and mortality and in the endemic overuse of expensive services, such as acute hospitalization and emergency department care. As the urban poor are disproportionately from ethnic minority backgrounds, this ineffective health care contributes, in part, to the widely noted racial and ethnic disparities in chronic disease outcomes. Case management programs have the potential to improve outcomes by helping patients overcome social and health system barriers to effective care. Yet case management programs are often not rigorously evaluated, or not rigorously evaluated in settings with predominantly urban poor patients. As a consequence, decision makers in health systems serving poor patients with chronic disease have insufficient empirical data to guide their decisions regarding investing in case management services rather than in traditional direct medical, psychiatric, and addiction treatment services. This proposal outlines a five-year career development plan for the candidate to become an independent investigator in clinical and health services research focused on the urban poor. The aim of the research proposal in this K23 application is to determine -- through a randomized, controlled trial -- whether a Multidisciplinary Case Management Program (MCMP) at an urban public hospital can improve the health care utilization and patient health, and lessen the public cost burden of frequently hospitalized patients with chronic diseases, when compared to usual care. The proposal also outlines a training program that will provide the candidate with additional training in biostatistics and research methods, cost-effectiveness analysis, health care improvement, and social science theory.